This invention relates to a transfer fabric for conveying wet paper from a sheet forming part to a hydro-extracting part and a papermaking machine using the fabric.
As means for receiving wet paper formed at a sheet forming part of a paper marking machine from a paper forming woven fabric of the machine and delivering the wet paper to a hydro-extracting part of the machine as the next step, a so-called needle felt obtained by applying vats of synthetic fibers one each to the obverse and the reverse face of a foundation formed by interweaving monofilaments or multifilaments and interlacing the vats by needling, and a wire which is a single-layer, double-layer woven fabric formed by using monofilaments have been known.
In a papermaking machine, delivery of wet paper is made at many places. This delivery process is generally effected by a forced aspirating device called transfer suction box or transfer suction roll. The method of harnessing the aspirating force is generally utilized because it is capable of most stably transferring wet paper. It nevertheless has disadvantages such as suffering the pressure of aspiration, when exerted more than that is proper, to extract fine fibers and filler together with water from the wet paper to the extent of adversely affecting the paper qualities, such as the evenness of surface smoothness on the obverse and the reverse side, curling property, and strength or inducing accelerated wear or abnormal wear on the paper forming woven fabric or felt. It also incurs higher cost for facilities and for maintenance and management thereof.
The needle felt has the vat densely gathered generally in the direction of z axis and, therefore, tends to accumulate fibers, filler, and chemical in the raw material for paper inside the body of felt. When a high-pressure washing shower is used for depriving the felt of such defiling substances, it tends to tear and bore holds in the vat of fibers and suffer from poor cleaning property. The papermaking machine of the type receiving the wet paper formed in the sheet forming part under nip pressure from the paper forming woven fabric and delivering the wet paper to the subsequent hydro-extracting part, therefore, is not allowed to increase the sheet forming speed but is prevented from improving the paper-producing property owing to the limited quality of the needle felt. For the purpose of conferring improved cleanability upon the needle felt, a woven fabric using monofilaments for both warps and wefts and keeping vats in an unneedled state have been tried. This woven fabric, however, has failed to withstand actual use because the transfer of water from the wet paper to the woven fabric is insufficient in the sheet forming part and the nip part and therefore the wet paper is not stably transferred to the woven fabric.
This invention, therefore, is aimed at providing a transfer fabric which is liberated from the drawback mentioned above and is enabled to manifest a satisfactory ability to transfer the wet paper and succumb fully to necessary cleaning and, as a result, improving the productivity of paper due to the use of this transfer fabric.
This invention relates to a transfer fabric used in a papermaking machine for receiving from a paper forming fabric the wet paper formed by a sheet forming part of the papermaking machine. The transfer fabric may be used for delivering the wet paper into a hydro-extracting part of the machine as the subsequent step. The transfer fabric is a clothed net produced by weaving plain yarn wefts of a small diameter so bound as to interpose water absorbing gaps therebetween on the running face side thereof and plain yarn wefts of a small diameter so bound as to interpose water absorbing gaps therebetween on the wet paper receiving face side and monofilament or twisted monofilament warps. The wefts are in a plurality of layers and the warps are in a single layer.
The warps of this invention can be monofilaments on the running face side of the fabric and can be monofilaments and/or plain yarns of a small diameter so bound as to interpose water absorbing gaps therebetween on the wet paper receiving face side of the fabric. The wefts can be disposed in a plurality of layers and the warps can be disposed in a plurality of layers.
The plain yarn wefts can be spun yarns, multifilaments, taslan finished yarns, twisted monofilaments, mole yarns, filament-processed yarns, yarns having spun yarns would on core lines of monofilaments, yarns having multifilaments wound on core lines of monofilaments, or yarns produced by co-twisting at least two kinds of yarns selected from any of yarns mentioned above.
A transfer fabric of the present invention may receive from the paper forming woven fabric wet papers formed by a plurality of sheet forming parts and delivers to the hydro-extracting part as the subsequent step the wet papers sequentially superposed in a plurality of layers.
The transfer fabric of this invention will be discussed more in detail below.